Reverse path imaging and transfixing copying method

ABSTRACT

Cut sheets of heat sensitive material are employed in carrying out a reverse path thermographic copying process wherein the imaging and fusing (a non-transfer mode of operation) or transfixing (a transfer mode of operation) are performed at a first station in response to radiant energy from a single source on a pre-development and post-development basis, respectively.

United States Patent 1191 Eichorn, deceased [4 1 Aug. 26, 1975 REVERSEPATH IMAGING AND TRANSFIXING COPYING METHOD [75] Inventor: Roger H.Eichorn. deceased, late of Rochester, NY., by Lincoln First Bank ofRochester, executor [73] Assignee: Xerox Corporation, Stamford,

Conn.

22 Filed: Dec. 27, 1973 [21] Appl. No.: 428,934

52 US. (:1. ..250/318; 101/470;-250 319; 355/3 DD 51 Int. Cl. H0lj 37/26[58] Field of Search ..250/316,317,31s,319; 101/470, DIG. 13-, 355/3 DD,16

[56] References Cited UNITED STATES PATENTS 3,048,695 8/1962 Russell250/3 l 8 Dulmagc 250/317 Jarvis l0l/470 Primary Examiner-James W,Lawrence Assistant Examiner--D. C. Nelms [57] ABSTRACT Cut sheets ofheat sensitive material are employed in carrying out a reverse paththermographic copying process wherein the imaging and fusing (anontransfer mode of operation) or transfixing (a transfer mode ofoperation) are performed at a first station in response to radiantenergy from a single source on a pre-development and post-developmentbasis, respectively.

8 Claims, 3 Drawing Figures PATENTEI] AUG 2 6 I975 SEIKU 1 BF 2 PATENTEDAuszsms va \JilLLl REVERSE PATH IMAGING AND TRANSFIXING COPYING METHODCROSS-REFERENCE TO RELATED APPLICATIONS This application is related tothe following copending and commonly assigned applications:

Serial No.

Applicant Filing Date Lincoln First Bank of Rochester. Executor forRoger H. Eichorn James D. Rees et al. Lincoln First Bank of Rochester.Executor for Roger H.'Eichorn Myron .I. Lenhard Lincoln First Bank ofRochester. Exeuctor for Roger H. Eichorn Lincoln First Bank of RochesterExecutor for Roger H. Eichorn DESCRIPTION OF THE INVENTION areconventionally carried out at separate stations.

If the imaging and fusing or transfixing stations are equipped withseparate heat sources. separate control mechanisms and transportmechanisms must be provided, and those mechanisms must be synchronizedso that the functions at each station are efficiently carried out.Obviously, this requires duplication of parts and a more complicatedsystem.

When the same heat source is provided for both stations, one is limitedto the same lamp intensity for both functions or the machine must belarger so that the lamp may be changed to a different intensity foreither fusing or transfixing after imaging.

It is an object of this invention to provide a copying method whichpermits the use of an inexpensive, simple compact copying deviceutilizing a cut sheet heat sensitive material.

It is proposed to accomplish the above object by using the same lamp andstation for the imaging and the fusing or transfixing functions.

Other objects of the invention will become apparent when the followingdescription in conjunction with the drawings wherein:

FIG. 1 is a schematic view of a copying apparatus showing the imagingand developing step;

FIG. 2 is a partial view of the copying apparatus of FIG. 1 illustratingthe position of a heat sensitive member after an image thereon has beendeveloped; and

FIG. 3 is a view of the apparatus of FIG. I showing a developed imagetransfer step.

Referring to the drawings. a copying apparatus I0 has a guide slot 12for receiving a sandwich of a heat sensitive sheet 14 and an originalsheet 16 with an image thereon. The heat sensitive sheet 14 comprises asupport with a heat sensitive coating. For example, the support may beanorganic film. such as a polyester film. cellulose acetate ortriacetate film, coated with a delayed tack adhesive which is normallyhard and nontacky at room temperature. but which, upon being activatedby heat to a tacky condition and subsequently cooled to roomtemperature. thereafter remain tacky for considerable periods of timevarying from at least 30 seconds to several days or more depending uponthe particular composition involved. Such delayed tack coatings are wellknown and can be a mixture of discrete particles or resin, such asindene resin or esterfied resin, and discrete particles of crystallineplasticizer. such as diphenyl phthalate or N-cyclohexyl paratoluenesulfonamide. The particles are bound together into the supporting filmby a binder. such as styrenebutadiene copolymer. Generally speaking. thecrystalline plasticizer component of the mixture is in excess of theresin component.

A cylinder 18 having a highly reflective surface is rotatably mounted onthe frame of the machine and a transparent belt 20 rotates around threeidler rolls 22, 24, 28 and a drive roll 26. The cylinder 18 and thedrive roll 26 are driven by a reversible motor (not shown). The rolls 24and 26 are arranged so that the belt 20 is pressed against the cylinder18 to form nips 25 and 27, respectively. A microswitch (not shown) islocated in the slot 12 and is electrically connected to the reversiblemotor for starting the same and is arranged to be actuated uponinsertion of sheets into the slot. Upon rotation of the cylinder 18, thebelt 20 will be rotated therewith and pressed against the surface of thecylinder. A radiation source, such as an incandescent lamp 30, isarranged opposite the cylinder 18 to apply radiant heat to the region ofthe cylinder 18 which is opposite the lamp. A delay mechanism isemployed to turn the lamp on and off at the proper time. Upon insertionof the original sheets 16 and the heat sensitive member 14 as a sandwichinto the slot I2 and into engagement with the nip 27. the sandwich willbe pulled past the lamp 30. A slot 31 is provided through which theoriginal sheet 16 emerges after being separated from sheet 14. A sheetseparator 33 is located at the entrance of the slot 31 and is undervacuum during a period necessary to attract the original thereto.thereby separating the same from the heat sensitive sheet 14.

A conveyor mechanism which comprises a belt 32 trained around a driveroll 34 and an idler roll 36. is located to coact with a roll 38 whichforms a pressure nip therebetween to grip the leading edge 39 of theheat sensitive sheet I4 to drive the same along a guide member 40 to adeveloper station which comprises a housing 4] having ferromagnetictoner particles 42 therein. The drive roll 34 is driven by the samemotor that drives the cylinder 18. A well known magnetic brush 44 ismounted on the housing 41 to have a portion rotatable in the toner bed42 and a portion arranged to engage the heat sensitive sheet I4 topresent toner thereto to develop the image thereon. The magnetic brush44 is also connected to the reversible motor which drives the cylinderI8 and the drive roll 34. The toner parti cles 42 comprise thermoplasticparticles pigmented with carbon black or other radiation absorbing dyesor pigments, and mixed with iron oxide particles.

A storage slot 50 is provided to receive the leading edge 39 of the heatsensitive sheet 14 after the same has passed the development station.The idler roll 36 is arranged relative to the surface 51 of the slot 50that the belt 32 makes slight contact with the surface 51 to grip theheat sensitive sheet 14 therebetween to move the same. A microswitch 52is located at the upper end of the storage slot 50 and is electricallyconnected to the reversible motor (not shown) which is connected to thecylinder 18, the drive roll 34 and the magnetic brush 44. The switch 52is arranged to be engaged by the leading edge 39 of the heat sensitivesheet 14. The location of the idler roll 36 is such that the trailingedge 53 of the heat sensitive sheet 14 will be engaged by the belt 32when the switch 52 is actuated by the leading edge 39. When the switch52 is actuated, reversal of the motor is effected which in turn effectsreversal of rotation of the drive roll 34, the magnetic brush 44 and thecylinder 18 to cause the reversal of movement of the heat sensitivesheet 14 out of the storage slot 50 past the development station andguide 40 up to the nip 27 and around the cylinder 18 past the lamp 30and out of the machine through slot 12.

A supply of copy paper 54 is arranged on a paper tray 56 and a feed roll58 is arranged to engage the uppermost one of the stack of copy papers54 to drive the same away from the stack along a guide member 60 to apair of nip rolls 62. A torsion spring 61 biases the paper tray 56toward the feed roll 58 and thereby brings the stack of copy paper intoengagement with the feed roll. The microswitch 52 is also electricallyconnected to a motor for driving the feed roll 58 and to another motorfor driving the nip rolls 62 and to a motor for supplying vacuum to theseparator 33. Upon actuation of the micro-switch 52 by the leading edgeof the heat sensitive sheet 14, the vacuum motor is turned off, themotor for the feed roll 58 is actuated to drive the same and a delaymechanism (not shown) for starting the nip rolls 62 is actuated to startthe nip rolls 62 after the leading edge of a copy sheet 54 is inengagement therewith and after the heat sensitive sheet 14 has moved ina reverse direction for a certain distance. A delay mechanism (notshown) is also employed for turning off the motors for the feed roll 58and for the nip rolls 62 at the appropriate time. The nip rolls 62,drive the copy sheet 54 into a guide 64 which leads the copy sheet tothe nip 27. This is so timed that the leading edge of the copy sheet 54arrives just prior to the nip 27 at the same time as the former trailingedge 53, but now the leading edge, of the heat sensitive sheet 14arrives thereat so that the two sheets will be aligned and moved by thecylinder 18 between the cylinder 18 and the belt past the lamp and outof the copying apparatus through slot 12 as a sandwich. A delaymechanism is timed to turn off the reversible motor for the cylinder 18and the drive roll 34 after the sheets 14 and 54 emerge from the slot12.

In operation, referring to FIG. 1, a heat sensitive sheet 14 and anoriginal sheet 16 having an image thereon to be copied are placedtogether to form a sandwich and inserted into slot 12 to actuate theswitch in the slot 12 to start the cylinder 18, belt 32 and the magneticbrush 44 rotating in the direction shown. The sandwich is fed betweenthe cylinder 18 and the belt 20 past the incandescent lamp 30 and isexposed to the lamp 30. The intensity of the lamp and the speed at whichthe sandwich passes thereby is such as to cause sufficient heat tocreate a tacky image on the heat sensitive member corresponding to theimage on the origi nal sheet 16. As the leading edge of the sandwichemerges from between the belt 20 and the cylinder 18, the original isseparated from the heat sensitive sheet 14 by vacuum separator 33 and isdischarged from the copying apparatus through the slot 31. The heatsensitive sheet 14 continues to the development station whereby themagnetic brush 44 dusts toner particles 42 onto the tacky image.Referring to FIG. 2, the developed heat sensitive sheet 14 passes intothe storage slot 50 and the leading edge 39 thereof engages themicroswitch 52 which causes reversal of rotation of the belt 32, themagnetic brush 44, and the cylinder 18 and actuation of the paper feedroll 58 and the delay mechanism for actuating the nip rolls 62.Referring to FIG. 3, upon reversal of the belt 32, the heat sensitivesheet 14 is removed from the storage area 50 with the former trailingedge 53 now being the leading edge. The sheet 14 is passed through thedeveloper station wherein magnetic brush 44 presents particles to theimage to develop the image with more toner particles if necessary. Atthis point, the leading edge of a copy paper 54 has been moved to thenip rolls 62 and the delay mechanism now actuates the nip rolls 62 todrive the copy sheet 54 to arrive just prior to the nip 27 at the sametime as the leading edge 52 of the heat sensitive sheet 14. The twosheets enter the nip 27 between the cylinder 18 and the belt 20 as asandwich and are exposed to the incandescent lamp 30 for a sufficientamount of time to melt the toner particles whereby a substantial portionthereof transfer from the heat sensitive sheet to the copy sheet and arefixed thereto due to the slight pressure between the sheets caused bythe pressure between the belt 20 and cylinder 18. Then the sandwich ispassed out of the copying apparatus through the slot 12 whereupon anoperator takes the sandwich and sep-' arates the sheets to obtain thecopy of the image on the original.

Inasmuch as the imaging and transfixing functions are separated not onlyby the development step but also by the storage of the heat sensitivesheet, provision may be made, if desired, to change the rate at whichthe heat sensitive sheet is advanced past the lamp and/or the intensityof the lamp during the interval of time that separates the imaging andtransfixing operations.

Rather than employing a transfer mode of operation, a non-transfer modemay be used wherein, the developed image is fused directly on the heatsensitive sheet 14 with the heat sensitive sheet being the copy itself.In that event, the cylinder 18, which will be contacted by the tonerparticles during the fixing or fusing step, must comprise a material towhich melted toner particles will not stick. Alternatively, a stack ofrelease sheets could be placed on the paper tray 56 and fed past thelamp 30 in contact with the developed image. In this latter case, therelease sheet will be of a material to which the toner particles willnot stick.

The control system and the components thereof for operating the machineas described are all well known and well within the grasp of one havingordinary skill in the art and therefore have not been shown.

What is claimed is:

l. A thermographic copying method comprising the steps of bringing a cutsheet of heat sensitive material into contact with an original bearingan image. to form a sandwich;

moving the sandwich in a first direction along a predetermined pathextending through a first station and a remotely spaced developmentstation;

exposing said sandwich at said first station to radiation from a radiantsource to thermally impart said image to said sheet;

separating said original from said sheet at a point between said firststation and said development station;

passing said sheet through said development station to at leastpartially develop said image while continuing to move said sheet in saidfirst direction along said path;

moving said sheet in the opposite direction along said path back throughsaid development station and said first station; and

re-exposing said sheet at said first station to radiation from saidsource to fix said image.

2. The method as recited in claim 1 wherein said image is furtherdeveloped as said sheet moves back through said development station insaid opposite direction.

3. The method as recited in claim I wherein one edge of said sheet isleading when said sheet is moving in said one direction and trailingwhen said sheet is moving in said opposite direction.

4. The method as recited in claim 1 wherein said image is developed byapplying resinous toner thereto.

5. The method as recited in claim 1 further including the additionalstep of depositing said sheet in a storage area after said sheet ismoved through said development station in said one direction and beforesaid sheet is moved back through said development station in saidopposite direction.

6. The method as recited in claim 1 wherein resinous toner is applied tothe image imparted to said sheet as said sheet is moved through saiddevelopment station in said first direction and said opposite directionto thereby develop said image.

7. The method as recited in claim 1 further including the step ofbringing said heat sensitive sheet into contact with a copy sheet at apoint between said first station and said development station while saidheat sensitive sheet is moving in said opposite direction along saidpath; and wherein said heat sensitive sheet is re-exposed while incontact with said copy sheet whereby said image is transfixed onto saidcopy sheet.

8. A method as recited in claim 1 wherein said image is fixed onto theheat sensitive sheet by the re-exposure step.

1. A thermographic copying method comprising the steps of bringing a cutsheet of heat sensitive material into contact with an original bearingan image, to form a sandwich; moving the sandwich in a first directionalong a predetermined path extending through a first station and aremotely spaced development station; exposing said sandwich at saidfirst station to radiation from a radiant source to thermally impartsaid image to said sheet; separating said original from said sheet at apoint between said first station and said development station; passingsaid sheet through said development station to at least partiallydevelop said image while continuing to move said sheet in said firstdirection along said path; moving said sheet in the opposite directionalong said path back through said development station and said firststation; and re-exposing said sheet at said first station to radiationfrom said source to fix said image.
 2. The method as recited in claim 1wherein said image is further developed as said sheet moves back throughsaid development station in said opposite direction.
 3. The method asrecited in claim 1 wherein one edge of said sheet is leading when saidsheet is moving in said one direction and trailing when said sheet ismoving in said opposite direction.
 4. The method as recited in claim 1wherein said image is developed by applying resinous toner thereto. 5.The method as recited in claim 1 further including the additional stepof depositing said sheet in a storage area after said sheet is movedthrough said development station in said one dirEction and before saidsheet is moved back through said development station in said oppositedirection.
 6. The method as recited in claim 1 wherein resinous toner isapplied to the image imparted to said sheet as said sheet is movedthrough said development station in said first direction and saidopposite direction to thereby develop said image.
 7. The method asrecited in claim 1 further including the step of bringing said heatsensitive sheet into contact with a copy sheet at a point between saidfirst station and said development station while said heat sensitivesheet is moving in said opposite direction along said path; and whereinsaid heat sensitive sheet is re-exposed while in contact with said copysheet, whereby said image is transfixed onto said copy sheet.
 8. Amethod as recited in claim 1 wherein said image is fixed onto the heatsensitive sheet by the re-exposure step.